" They had forgotten much, but they did not know it. They were as perfectly fitted to their environment as it was to them—for both had been designed together. What was beyond the walls of the city was no concern of theirs; it was something that had been shut out of their minds. Diaspar was all that existed, all that they needed, all that they could imagine. It mattered nothing to them that Man had once possessed the stars. "

― Arthur C. Clarke , The City and the Stars